Mi-Fi v/s Increasing Data Package thru AT&T

Me and my family took a little trip up to Stone Mountain, GA this past Thursday and Friday. I used my iPhone 5 and Apple Maps on the trip to Stone Mountain, which is about 4 hours from where I live. We went up thru Pine Mountain, Ga and Senoia, GA, so a lot of back country roads. Apple Maps worked perfect for me. Never missed a beat and brought me to the front door of every place we went. I currently have the 200 mb data package from AT&T which I think has been updated to 300 mb now. During our trip I got a data usage warning from AT&T that I had used 65% of my data allowance. I checked with AT&T and I can upgrade to a 4 GB shared data plan that will also allow me to use the Hotspot feature on my phone. My question is this. Should I buy a Mi-Fi device that I can pay for a data package when needed, such as a trip, or would you upgrade the data package, which I will have to pay $20.00 more a month every month? Sorry for the long post...

MacRumors attracts a broad audience
of both consumers and professionals interested in
the latest technologies and products. We also boast an active community focused on
purchasing decisions and technical aspects of the iPhone, iPod, iPad, and Mac platforms.